Magnetic heads are provided in computers for transferring information between the magnetic heads and storage media such as discs disposed in contiguous (almost abutting) relationship to the heads. The magnetic media such as the discs are rotated by disc drives under the control of microcomputers to particular positions where the transfer takes place. When the transfer is from the disc drive to the magnetic head, the information read by the magnetic head is processed in the computer and the processed information is then transferred from the head to a storage position in the disc. The information transferred between the head and the disc is generally in binary form.
The rate of transferring binary information between the head and the storage medium such as the disc has been progressively increasing through the years. In order to transfer such information at progressively increasing rates, the size of the heads has been progressively decreased. Furthermore, as the size of the heads has progressively decreased, the precision in the manufacture of parts in the head has had to progressively increase in order to be able to transfer the binary information accurately between the head and the disc drive at the increased rates.
The magnetic heads include members which face the magnetic discs and protect the magnetic heads in case the magnetic discs should crash against the magnetic heads as the discs rotate at high speeds. These members may be made from a suitable insulating material such as an aluminum oxide with an index of refraction of at least 1.63 to provide the members with hard and dense characteristics. These members have decreased in size in accordance with the decrease in size of the heads. Furthermore, the dimensions of these members have had to become more precise as the size of these members has decreased and as the rates of transfer of the magnetic information between the heads and the discs have increased because of the rotation of the discs at increased speeds and because of the decreased size of these members. These members have been formed as die on a substrate.
Even as the size of the die on the substrate has tended to decrease through the years, the size of the substrate has tended to increase. As the size of the substrates has tended to increase, it has become progressively difficult to fabricate the members on the die with great precision. For example, when the substrate has a width of approximately six inches (6"), hundreds, if not thousands, of the members may be simultaneously produced on the substrate. Any slight deviation in dimension at one end of the substrate may become magnified in die which are progressively disposed on the substrate toward the other end of the substrate.
The substrates are often fabricated on a one-at-a-time basis in processing equipment. As will be appreciated, this fabrication is relatively slow even though there may be hundreds, if not thousands, of die on a single substrate. Processing equipment also exists for directing a plurality of substrates in sequence through a plurality of successive stations. Although this may be considered to constitute an improvement from a time standpoint, it still provides a processing of only a single substrate at any one time at each successive processing station.
It is desirable to process a plurality of substrates simultaneously to provide a deposition on each of the substrates with the same parameters. It is also desirable to process each of the substrates in the plurality simultaneously with great precision in each of the successive processing steps. This desirability of being able to process a plurality of substrates simultaneously with great precision has been recognized for some time but no one has been able to accomplish this until now. This has been particularly true in fabricating substrates each of which has hundreds, if not thousands, of die for use as members in magnetic heads.
It is further desirable to provide one (1) apparatus which operates on an automatic basis to process a plurality of substrates from the steps of receiving the substrates from a cassette module to the steps of positioning the substrates on planets and then to the steps of providing controlled depositions on planets. It is further desirable to provide apparatus which operates on an automatic basis to return the substrates to the cassette module after the controlled depositions on the substrates.